Milk‑derived exosomes exert anti‑inflammatory activity in lipopolysaccharide‑induced RAW264.7 cells by modulating the TLR4/NF‑κB and PI3K/AKT signaling pathways

Inflammation is a protective response that occurs when the body is injured and is a primary pathological process that occurs in certain diseases, such as inflammatory bowel diseases, osteoarthritis and acute lung injury. Milk-derived exosomes (M-Exos) contain various physiologically active substances related to immunity. These substances can act on cells to lessen the damage attributed to inflammation. The present study aimed to extract M-Exos and explore the protective mechanism of M-Exos on the lipopolysaccharide (LPS)-induced inflammatory response in RAW 264.7 cells, a mouse macrophage cell line. Ultra-high speed cryo-centrifugation was used to extract M-Exos. Transmission electron microscopy, nanoparticle tracking analysis and western blotting were used to identify the M-Exos. Western blotting, reverse transcription-quantitative PCR and ELISA were used to analyze cellular inflammatory factors, oxidative stress factors and relevant inflammatory signaling pathways. These results indicated that treatment with M-Exos led to a notable recovery in cell viability and an improvement in the intracellular glutathione reduction induced by LPS. Reduced secretion of pro-inflammatory factors nitric oxide, IL-6 and TNF-α were also observed, as well as decreased expression levels of the oxidative stress factors nitric oxide synthase and cyclooxygenase-2. Furthermore, M-Exos could impact inflammation by regulating the toll-like receptor 4/NF-κB and PI3K/AKT signaling pathways and reducing apoptosis. Therefore, M-Exos may serve as a nutritional component of anti-inflammatory food, which could influence the occurrence and development of inflammation.